02 Change Data Model JAVASCRIPT C001

import Warning from 'components/Markdown/Warning' import Code from 'components/Markdown/Code' import Info from 'components/Markdown/Info'

export const meta = { title: 'Change Datamodel', position: 2, nextText: 'Fantastic! 🎉 You are now able to migrate your database using Prisma. Next you will learn how to build an API server based on Prisma client.', technology: 'node', technologyOrder: 1, gettingStartedOrder: 1, articleGroup: 'Change Datamodel' }

Goals

On this page, you will learn how to:

• Adjust the datamodel and update your Prisma API
• Regenerate your Prisma client
• Create two database records in a single transaction
• Query relational data

This page is only relevant if you started with a new database or a Demo server. If you configured Prisma with an existing database, you need to run migrations directly against your database.

Adjust your datamodel

Update the datamodel in datamodel.prisma as follows:

<Code languages={["SQL", "MongoDB"]}>

type User {
  id: ID! @unique
  email: String @unique
  name: String!
  posts: [Post!]!
}

type Post {
  id: ID! @unique
  title: String!
  published: Boolean! @default(value: "false")
  author: User
}

type User {
  id: ID! @id
  email: String @unique
  name: String!
  posts: [Post!]! @relation(link: INLINE)
}

type Post {
  id: ID! @id
  title: String!
  published: Boolean! @default(value: false)
  author: User
}

Here's what changed:

• You added a new email field to the User type.
• You added a new Post type to the datamodel.
• You added a relation between User and Post (via the posts and author fields).

Redeploy your Prisma API

To apply the changes you just made to your datamodel, you need to redeploy the Prisma datamodel:

prisma deploy

Regenerate your Prisma client

Because the Prisma client is based on your datamodel, it needs to be regenerated every time the datamodel is updated:

prisma generate

The Prisma client library in the /generated/prisma-client directory is now being updated and its API has been adjusted to use the new datamodel.

You can ensure that your Prisma client is automatically being updated after every deploy by adding the following lines to your prisma.yml:

hooks:
  post-deploy:
    - prisma generate

Read and write nested objects

The Prisma client API allows to write nested objects in a single transaction without having to manually control when the transaction starts or ends.

The MongoDB database connector currently does not support ACID transactions. Learn more in this GitHub issue.

Update your index.js to look as follows:

const { prisma } = require('./generated/prisma-client')

// A `main` function so that we can use async/await
async function main() {

  // Create a new user with a new post
  const newUser = await prisma
    .createUser({
      name: "Bob",
      email: "[email protected]",
      posts: {
        create: [{
          title: "Join us for GraphQL Conf in 2019",
        }, {
          title: "Subscribe to GraphQL Weekly for GraphQL news",
        }]
      },
    })
  console.log(`Created new user: ${newUser.name} (ID: ${newUser.id})`)

  // Read all users from the database and print them to the console
  const allUsers = await prisma.users()
  console.log(allUsers)

  const allPosts = await prisma.posts()
  console.log(allPosts)
}

main().catch(e => console.error(e))

Run the script with the following command:

node index.js

Query relational data

With the Prisma client API, you can navigate relations in your data graph using chained method calls (also called fluent API). Here is how you can query the posts written by a certain User:

const { prisma } = require('./generated/prisma-client')

// A `main` function so that we can use async/await
async function main() {

  // Read the previously created user from the database and print their posts to the console
  const postsByUser = await prisma
    .user({ email: "[email protected]" })
    .posts()
  console.log(`All posts by that user: ${JSON.stringify(postsByUser)}`)

}

main().catch(e => console.error(e))